While the concept of weight reduction using high tech materials is not new, elimination of excess mass and inertia continues to make the difference between success and failure in the design of motion control and automation systems. Machine design engineers aim for energy savings, higher throughput rates and reduced downtime without compromising on quality or accuracy.

R+W’s SL Series torque limiters address this requirement with half the inertia and less than half the mass, allowing for a rapid and automatic recovery from torque overload even in the most advanced drive technology.

Many users prefer to control torque overload through electronic current limitation instead of the outdated mechanical torque limiters. While this is effective in many cases as machinery becomes more dynamic, the inertia of moving parts becomes more critical.

It is possible to abruptly decelerate a rotating mass through unintentional blockage or application of a dynamic braking system at a faster rate than the drive would normally accelerate. This creates torque overload through reflected inertia, which is completely independent of the electronic system, and can easily exceed the peak torque rating of the motor.

The modern torque limiters display a high level of sensitivity and accuracy, with increasingly smaller impact on the size, mass, balance and power consumption of the drive system.

The SL Series of torque limiters utilises the proven spring-loaded ball detent system, along with a previously patented preload for zero backlash operation. R+W designed the product from the ground up over a period of two years to achieve the 50% weight reduction in their torque limiters.

SL Series automatic torque limiters also offer unparalleled power density. In addition to custom material specifications, the torque limiters also incorporate specially designed spring systems and some improvements to the ball detent configuration resulting in a 40% increase in torque capacity for a given size while the weight reduction was achieved through the compression of individual components without negative impact on the precision or service life of the torque limiter.

The SL Series can handle in excess of 10,000 disengagement events, depending on rotational speed.

R+W offers their torque limiters in four sizes (Series 30/ 60/ 150/ 300) to cover disengagement torque values from 5Nm to 700Nm with choice of mounting options including direct and indirect drive versions.

Models SLN (clamping) and SLP (keyway) attach by flange to sprockets, sheaves, pulleys and gears. These torque limiters also include an integral dual bearing system to support belt and chain tension when properly located over the shaft.

Models SL2 (bellows coupling) and SLE (servo insert coupling) mount inline between two independently supported shafts such as motor to ball screw connections and compensate for the small but inevitable misalignment.

All four models are field adjustable torque limiters, and come with both English and metric bores according to customer specifications.

The SL Series proves the need for mechanical torque limiters in cutting edge machinery design with its size and weight advantages.

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